Black Sea Lowland. (Map: Black Sea Lowland.) A great low plain in southern Ukraine, extending from the chain of in the north (, , , and ) and the northeast ( and ) to the and the in the south; from the in the west to the Lower-Don Lowland in the east. The northern boundary of the Black Sea Lowland is not definite: it is defined by the line of the extreme outcroppings of the layers of the Ukrainian Crystalline Shield. The is a part of the Black Sea Lowland. The width of the Black Sea Lowland varies from 50 km in the west and the east to 180 km in the middle. The eastern part of the lowland—the —narrows down to 10–20 km. The Black Sea Lowland lies wholly within the boundaries of the historical-geographical region known as and comprises almost a half of its territory. By its tectonic structure the Black Sea Lowland is a part of the , which consists of thick, almost horizontal layers of sediment, mostly Paleocene and Neocene sea deposits (various clays, sands, limestones, sandy clays, and sandy limestones) overlaid with continental deposits of the Anthropogene period (reddish-brown clays, usually over 20 m deep, and loessial loams). Tertiary deposits are exposed only in river and in some places on the sea coast. The Black Sea Lowland was covered by the Pontic Sea as recently as the Lower Pliocene. Eventually it became dry land, dissected by a few small . This process was cut short by the uplifting of the sea, which flooded the river mouths and caused to form. Now the Black Sea Lowland is an accumulative, weakly divided plain, which gradually slopes towards the and the (from 160 m in the north to 10–15 m in the south) and usually meets the seas by a steep drop. The lowland is dissected by a fairly thin network of river of the Dnister River, , , Inhulets River, , , and lesser rivers. The depth of the valleys varies from 80 m in the north to 20–25 m in the south. The river valleys are broad and distinct, with three to five accumulative terraces. Landslips have developed on the steep right slopes of the valleys. The mouths of the that enter the sea widen out and form . Broad swampy terraces or are characteristic of the valleys of the larger rivers, such as the Dnipro River, , and . The slopes are cut by many gullies and ravines. The gullies have a southerly direction and cut into the intervalley plains. The most dissected surface is the western part of the lowland, between the Danube and the Boh; somewhat less dissected is the middle part between the and the Dnipro River; and the least dissected is the part between the and the . The extensive intervalley plains are infrequently and weakly complicated by shallow, closed depressions called pody, which fill with meltwaters in the spring, and by smaller, saucerlike hollows. These two formations are prevalent in the eastern part of the lowland and are also found in the central part. Numerous burial mounds rise up to 10 m above the flat steppe. A unique landscape is presented by the alluvial plain on the left bank of the lower called (a waterless, sandy plain that was once the ), and by the area on both sides of Syvash Lake, which was formed as the sea advanced on the dryland. The most variegated landscape is found on the sea coast, and it results from the interaction of various forces on the sea-land borderline. BIBLIOGRAPHYBondarchuk, V. Heomorfolohiia URSR (Kyiv 1949)—Heolohichna budova Ukraïns'koï RSR (Kyiv 1963)Lan'ko, A.; Marynych, O.; Shcherban', M. Fizychna heohrafiia Ukraïns'koï RSR (Kyiv 1969) Volodymyr Kubijovyč [This article originally appeared in the Encyclopedia of Ukraine, vol. 1 (1984).] , Black Sea Lowland The Black Sea Lowland or Cisblack-sea Lowland (Ukrainian: Причорноморська низовина, romanized: Prychornomrska nyzovyna) is a major geographic feature of the Northern Pontic region and the East European Plain. It is almost completely within Southern Ukraine covering half of its territory., By its tectonic structure the Black Sea Lowland is a part of the Black Sea Depression, which consists of thick, almost horizontal layers of sediment, mostly Paleocene and Neocene sea deposits (various clays, sands, limestones, sandy clays, and sandy limestones) overlaid with continental deposits of the Anthropogene period (reddish-brown clays .